Tris-buffered efficacy: enhancing stability and reversibility of Zn anode by efficient modulation at Zn/electrolyte interface

Aqueous zinc-ion batteries (AZIBs) have developed rapidly in recent years but still face several challenges, including zinc dendrites growth, hydrogen evolution reaction, passivation and corrosion. The pH of the electrolyte plays a crucial role in these processes, significantly impacting the stability and reversibility of Zn²⁺ deposition. Therefore, pH-buffer tris (hydroxymethyl) amino methane (tris) is chosen as a versatile electrolyte additive to address these issues. Tris can buffer electrolyte pH at Zn/electrolyte interface by protonated/deprotonated nature of amino group, optimize the coordination environment of zinc solvate ions by its strong interaction with zinc ions, and simultaneously create an in-situ stable solid electrolyte interface membrane on the zinc anode surface. These synergistic effects effectively restrain dendrite formation and side reactions, resulting in a highly stable and reversible Zn anode, thereby enhancing the electrochemical performance of AZIBs. The Zn||Zn battery with 0.15 wt% tris additives maintains stable cycling for 1500 h at 4 mA·cm⁻² and 1120 h at 10 mA·cm⁻². Furthermore, the Coulombic efficiency reaches ~ 99.2% at 4 mA·cm⁻²@1 mAh·cm⁻². The Zn||NVO full batteries also demonstrated a stable specific capacity and exceptional capacity retention.

Graphical abstract